| 1. |
- Roman, Diana, et al.
(författare)
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Mechanisms of Unrest and Eruption at Persistently Restless Volcanoes: Insights From the 2015 Eruption of Telica Volcano, Nicaragua
- 2019
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Ingår i: Geochemistry, Geophysics, Geosystems. - 1525-2027. ; 20:8, s. 4162-4183
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Tidskriftsartikel (refereegranskat)abstract
- Many of Earth's volcanoes experience well-defined states of “quiescence” and “unrest,” with unrest occasionally culminating in eruption. Some volcanoes, however, experience an unusually protracted (i.e., decades-long) period of noneruptive unrest and are thus categorized as “persistently restless volcanoes” (PRVs). The processes that drive persistently restless volcanism are poorly understood, as our knowledge of PRVs is currently based on a small number of case studies. Here we examine multidisciplinary observations of the 2015 eruptive episode at Telica Volcano, Nicaragua, in the context of its long-term behavior. We suggest that the latter phases of the 2015 eruption were ultimately driven by destabilization of its shallow magma reservoir. Based on previous geodetic-seismic studies of Telica (Geirsson et al., 2014, https://doi.org/10.1016/j.jvolgeores.2013.11.009; Rodgers et al., 2013, https://doi.org/10.1016/j.jvolgeores.2013.08.010 and 2015, https://doi.org/10.1016/j.jvolgeores.2014.11.012) and on multiparameter observations at Telica over a 7-year period, we propose that three distinct states of unrest occur at Telica over decadal timescales: a stable open state involving steady conduit convection and two distinct “unstable” states that may lead to eruptions. In the “weak sealing” state, phreatic explosions result from steady conduit convection underlying a weak seal. In the “destabilized” state, destabilization of the top of the convecting magma in the conduit leads to rapid accumulation of high pressures leading to strong/impulsive phreatomagmatic explosions. Our observations and interpretations suggest that continuous seismic, ground-based deformation, gas emission, and thermal monitoring and interpretation of these data within a paradigm of sustained conduit convection modulated by episodes of sealing and destabilization of shallow magma reservoirs may allow robust forecasting of eruption potential, energy, and duration at Telica and similar PRVs worldwide.
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| 2. |
- Smets, Benoît, et al.
(författare)
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Detailed multidisciplinary monitoring reveals pre- and co-eruptive signals at Nyamulagira volcano (North Kivu, Democratic Republic of Congo)
- 2014
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Ingår i: Bulletin of Volcanology. - : Springer Science and Business Media LLC. - 0258-8900 .- 1432-0819. ; 76:787, s. 1-35
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents a thorough description of Nyamulagira’s January 2010 volcanic eruption (North Kivu, Democratic Republic of Congo), based on a combination of field observation and ground-based and space-borne data. It is the first eruption in the Virunga Volcanic Province that has been described by a combination of several modern monitoring techniques. The 2010 eruption lasted 26 days and emitted ∼45.5 × 106 m3 of lava. Field observations divided the event into four eruptive stages delimited by major changes in effusive activity. These stages are consistent with those described by Pouclet (1976) for historical eruptions of Nyamulagira. Co-eruptive signals from ground deformation, seismicity, SO2 emission and thermal flux correlate with the eruptive stages. Unambiguous pre-eruptive ground deformation was observed 3 weeks before the lava outburst, coinciding with a small but clear increase in the short period seismicity and SO2 emission. The 3 weeks of precursors contrasts with the only precursory signal previously recognized in the Virunga Volcanic Province, the short-term increase of tremor and long period seismicity, which, for example, were only detected less than 2 h prior to the 2010 eruption. The present paper is the most detailed picture of a typical flank eruption of this volcano. It provides valuable tools for re-examining former—mostly qualitative—descriptions of historical Nyamulagira eruptions that occurred during the colonial period.
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